Trigonometry

Ratios

sin = P/H, cos = B/H, tan = P/B

Standard values

sin 30° = ½, sin 45° = 1/√2, sin 60° = √3/2

cos is the reverse order

tan values

tan 30° = 1/√3, tan 45° = 1, tan 60° = √3

Pythagorean identity

sin²θ + cos²θ = 1

Other identities

1 + tan²θ = sec²θ, 1 + cot²θ = cosec²θ

Complementary angles

sin(90° − θ) = cos θ, tan(90° − θ) = cot θ

Double angle

sin 2θ = 2 sinθ cosθ, cos 2θ = cos²θ − sin²θ

Pythagoras theorem

H² = P² + B²

Triplets: 3-4-5, 5-12-13, 8-15-17, 7-24-25

sin(A ± B)

sin A cos B ± cos A sin B

cos(A ± B)

cos A cos B ∓ sin A sin B

tan(A + B)

(tan A + tan B) / (1 − tan A tan B)